In modern life, traveling around the world is a very common leisure activity, and people usually bring luggage to travel. However, when people want to go shopping, it is a great burden to go shopping with luggage. Therefore, the traveler generally stores the luggage in a locker at a station, and then goes shopping. At present, a common locker usually includes several accommodating spaces with a few fixed sizes. For example, an accommodating space of a small size is for storing leather bags, an accommodating space of a middle size is for storing hand baggage, and an accommodating space of the largest size is for storing luggage cases.
However, the number of lockers with different sizes is limited, so people usually find that the size of locker that they need is not available, and they may use another locker of another size. When the size of an available locker has a larger accommodating space than the people need, the extra space is not used and is wasted. Consequently, it is a big issue to consider and study to develop a locker whose accommodating spaces can be used properly.